Below are the typical rejection (removal) percentages of a standard thin film (TFC) reverse osmosis membrane. These are averages based on experience and are generally accepted within the industry. They are not a guarantee of performance. Actual rejection can vary according to the chemistry of the water, temperature, pressure, pH and other factors.

Estimated Reverse Osmosis Rejection Percentages

The reverse osmosis process uses a semi-permeable membrane to reject a wide variety of impurities. Here is a partial list.

Aluminum

97-98%

Nickel

97-99%

Ammonium

85-95%

Nitrate

93-96%

Arsenic

94-96%

Phosphate

99+%

Bacteria

99+%

Polyphosphate

98-99%

Bicarbonate

95-96%

Potassium

92%

Boron

50-70%

Pyrogen

99+%

Bromide

93-96%

Radioactivity

95-98%

Cadmium

96-98%

Radium

97%

Calcium

96-98%

Selenium

97%

Chloride

94-95%

Silica

85-90%

Chromate

90-98%

Silicate

95-97%

Chromium

96-98%

Silver

95-97%

Copper

97-99%

Sodium

92-98%

Cyanide

90-95%

Sulphate

99+%

Ferrocyanide

98-99%

Sulphite

96-98%

Fluoride

94-96%

Zinc

98-99%

Iron

98-99%

Lead

96-98%

Insecticides

97%

Magnesium

96-98%

Detergents

97%

Manganese

96-98%

Herbicides

97%

Mercury

96-98%

Virus

99+%

TDS (Total Dissolved Solids)

95-99%

Hardness

93-97%

Figures given above are not actual test figures but are manufacturers’ estimates of normal TFC membrane performance